The CN band spectrum of Comet Bennett 1970 II was photographed on April 14, 1970. In addition to the (0,0) band, some other faint lines were observed, which arise either from the (1,1) band of the normal isotopic species or from the (0,0) band of 13CN. The Swings effect was investigated theoretically and found to give good agreement with observation. An estimate is made of the pure rotational transition rate in the ground state of CN. Absolute intensities of the CN lines were found by comparison with the lunar spectrum. From these measurements the distribution, density and total mass of cyanogen in the gaseous coma of the comet are estimated.